This invention relates to surgical instruments. In particular this invention relates to saw blades for making surgical cuts.
Surgical saw blades for use with powered surgical saws are well known. Generally they are relatively thin (approximately 0.030 inches) surgical steel elements having staggered teeth on a cutting edge. The degree of stagger is often approximately half the material thickness, i.e. 0.015 inches above the plane of the top surface of the saw blade and 0.015 inches below the plane of the bottom surface of the surgical saw. Thus, because of the stagger, a saw which is 0.030 inches in thickness ordinarily makes a cut which is at least 0.060 inches thick.
Surgical saws so structured have presented a plurality of problems. When used with a flat guide surface then tend to flex in response to the efforts of the surgeon to hold the blade flat on the guide surface. The problem of flexing is particularly troublesome when the surgeon is performing "skimming" cuts, i.e. cuts where only very slightly thicknesses of bones are to be removed. Thin surgical saw blades tend to flex and be deflected away from the desired plane of the cut. Such flexion results in surgical difficulties and worse, may result in uneven resectioned surfaces.
Another problem with the known blade structures is that they are not conductive for use with capture slot type guides, i.e. guides which are defined by slots rather than uni-planar surfaces. Where such slots are closed-ended, because of the saw tooth's stagger, the slot width must be substantially greater than the thickness of the blade so as to permit passage of the toothed portion therethrough.
Even when a capture slot is open at one end, the slot width must be substantially greater than the blade thickness or the guide containing the slot must be positioned away from the bone being resectioned to permit room for the staggered teeth of the blade to be introduced between the bone to be cut and the guide. Such displacement of the guide from the bone to be cut is recognized by most surgeons to be undesirable.
An apparently obvious solution to the flexion problem is to increase the blade thickness. In prior blade design philosophy, however, increasing the blade thickness was unacceptable because as the blade thickness increased, so did the tooth stagger tooth size and cut width. Thick staggered teeth are known to increase cutting effort and to generate excessive heat during cutting. Neither of these conditions is desirable.